A tilt adjustment-locking mechanism for a seat back of the known type such as disclosed in DE 43 04 725 C2 includes two locking mechanism parts engaged together via the toothed areas of a tumbler drive whose flange areas are firmly connected to the seat back or seat body. Areas of the locking mechanism parts are gripped about their circumference by clamping areas that hold the locking mechanism parts opposite each other in order to accept the large axial forces or inertia that may arise during a crash. This protection from lateral loads is insufficient however. This design has already been improved upon in that an additional radially-deviating clamping area is provided during the tilt process. Even this additional clamping area can only partly solve the problem.
Another adjustment drive is known as described in DE 696 00 369 T2 whose opposing rotatable disks are held together by means of a clamping area that grips and encloses the outer circumference as a ring. One of the disks is welded to the seat body and the other disk is welded to the seat back. The welded connection can easily lead to displacement of the disks. Therefore, a similar design is not suitable for a tumbler drive providing a precise guide. Furthermore, the connection formed by this adjustment drive between the seat back and the seat body is permanent, so that the seat body and seat back may be upholstered and covered only as a unit.
Based on this state of the art, the invention has the task of forming a tilt adjustment-locking mechanism of a type so that the interlocking toothed areas remain engaged even when influenced by large forces. The solution of this task is provided by a tilt adjustment-locking mechanism for a seat back, comprising a fixed locking mechanism part; a rotating locking mechanism part; a rotatable cam, for connecting the fixed locking mechanism part connected to the rotating locking mechanism.
The fixed locking mechanism part includes an interior toothed area adapted to mate with an exterior-toothed area forming a part of the rotating locking mechanism part. At least one of the fixed and rotating locking mechanism parts includes a polygonal circumference area with polygonal surfaces that fit into correspondingly shaped first and second receptor openings disposed on the seat back or seat body.
The polygonal surfaces match with opposing surfaces without rotating. At least an exterior circumference of the fixed and rotating locking mechanism parts is overlapped by a clamping area on a clamping ring.
The tilt adjustment-locking mechanism based on the invention also provides protection against disengagement of the meshing toothed areas in the case of a crash. Advantageous embodiments of the invention arise from the claims and description of the present invention.
In one advantageous embodiment, the seat back is connected with the seat body so that they may be separated despite of the completely-surrounded circumferential clamping area, so that either part may be exchanged at any time. Welded joints may be excluded without reducing the strength of the connection. Even with a locking ring that surrounds both locking mechanism parts, the torque load-bearing ability is not reduced by means of its polygonal circumferential shape.